I would be willing to bet that the inside washer gets like that due to the play in between the diff cup and the outdrives. Mine got real bad. I noticed that the brass insert had worn so badly that when you would bobble the outdrive, it would place alot of pressure the sungear pin, which would press into the washer you are talking about.

I would sure love to have steal instead of brass in a high wear area like that. wink wink someone